The invention relates to spin casting die assemblies, and more particularly, to end caps for spin cast die assemblies which have inserts which must be axially retained during the spin casting process.
There are known spin cast die assemblies which have a hollow cylindrical outer housing or casing in which a hollow cylindrical insert is inserted. Such an insert must be retained within the casing and held axially against an annular shoulder in the casing. To maintain the insert against the casing shoulder end cap assemblies have been attached to the end of the casing. One type of end cap assembly, which has been in use for around 50 years, includes a locking ring with exterior ramped flanges and an outer cap which is bolted onto to the end of the casing. The outer cap has cam surfaces which cooperate with the flanges to cause the locking ring to move axially inwardly to clamp the insert in place as the locking ring is rotated. To rotate the ring into and out of position requires an unpowered manually operated steering wheel unit (for small die assemblies) or hydraulically operated hammering/ratcheting mechanism (for large die assemblies), and the locking ring must be capable of withstanding high temperatures. The locking rings have to be replaced often as a result of being hammered into and out of place.
Another type of end cap is bolted onto the end of the casing and includes external flyweights. As the assembly is spun, the flyweights pivot and urge an inner ring axially inwardly towards the insert. But, such external flyweights can interfere with the spin cast die assemblies being rolled from one location to another, and can prevent such an assembly from being used in a spinner cabinet.
Accordingly, an object of this invention is to provide a spin cast die assembly with an end cap mechanism which does not have to be hydraulically hammered into and out of place.
A further object of the invention is to provide such a spin cast die assembly with an end cap mechanism which can withstand high temperatures.
Another object of the invention is to provide such a spin cast die assembly with an end cap mechanism which does not have external parts, such as flyweights, which interfere with movement of the spin cast die assemblies or which prevent use of the assembly in spinner cabinet.
These and other objects are achieved by the present invention, wherein a spin cast die assembly includes a casing, an insert and an end cap assembly for retaining the insert against an annular shoulder within the casing. The end cap assembly has a mounting ring attached to an end of the casing. The mounting ring receives a flyweight ring which engages an end of the insert and which pivotally supports a plurality of flyweight members which are mounted radially internally with respect to the mounting ring. The mounting ring has an annular flyweight engagement surface which faces generally radially inwardly and towards the shoulder. As the assembly is spun, the inner ends of the flyweight members pivot radially outwardly. The flyweight members thereby cooperate with the flyweight engagement surfaces of the mounting ring to cause the flyweight rings to move axially towards the insert and thereby force the insert against the shoulder.